There is a new complete transmit audio system now in production. I have replaced my Behringer and Innovonics 223 gear with the MAX audio processor. It is a KIT with conventional thru hole mounting components. The makers are developing a network of kit assemblers, if you feel you cannot assemble a board. Complete assembled boards may become available later. Make inquiry of the MAX people to find the most current status.

The MAX includes everything you need for a complete AM audio processing system. It is available in a variety of enclosures. Most importantly, it includes a "hard limiter" which will prevent modulation peaks exceeding 100% negative, something AM transmitters such as the K7DYY Super Senior need to eliminate protection trips and achieve the dense distortion free audio you want.
The MAX Audio Processor can be mounted in a 1 rack unit height enclosure as shown below. It also comes as a desktop cabinet style. It has a unique compressor circuit that totally eliminates the K7DYY fan noise from the transmitted signal, while still providing robust modulation. The peak limiter can be set for either symmetrical modulation or +120% peaks for more audio punch. It will completely eliminate protection trips from overmodulation.

The MAX audio processor output low pass filters have a very steep slope, and have a wide variety of choices for transmitted bandwidth. Up to 3 filters can be switched from the front panel, and can be internally set to anything you want. I have mine set for 3, 4, and 5 KHz audio (@ -3 dB). The 3 KHz setting is perfect to operate on 7295 or 3705 KHz near the band edges with confidence you will not be out of band. The 5 KHz setting gets good reports when conditions allow a wider signal. I built one of the prototypes for N9PVF to eliminate his K7DYY protection trips, and it corrected the problems he was having. I demonstrated that prototype at the Antique Wireless Association convention in Rochester. (By contrast, the Innovonics 223 has many complex menus and internal levels to set and the only filter suitable for amateur radio is 5 KHz.) As you can see, the MAX audio processor is easy to set up, and is a perfect match for trouble free operation with the K7DYY Super Senior full legal limit transmitters.

I plan to try the MAX audio processor with my Viking II classic tube AM transmitter as well as my modern Yaesu FTDX101.

To purchase a MAX audio processor, Go to: https://www.internetwork.com/MAX/

To hear a demonstration of the functions and performance and review of the MAX audio processor from a user, WA3VJB, watch: https://www.youtube.com/watch?v=R9zsypghPko

To see reviews from other users, go to: https://www.eham.net/reviews/view-product?id=15743